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.Dd April 1, 2007
.Dt VHOLD 9
.Os
.Sh NAME
.Nm vhold , vdrop , vdropl
.Nd "acquire/release a hold on a vnode"
.Sh SYNOPSIS
.In sys/param.h
.In sys/vnode.h
.Ft void
.Fn vhold "struct vnode *vp"
.Ft void
.Fn vholdl "struct vnode *vp"
.Ft void
.Fn vdrop "struct vnode *vp"
.Ft void
.Fn vdropl "struct vnode *vp"
.Sh DESCRIPTION
The
.Fn vhold
and
.Fn vholdl
functions increment the
.Va v_holdcnt
of the given vnode.
If the vnode has already been added to the free list and is still referenced,
it will be removed.
.Pp
The
.Fn vdrop
and
.Fn vdropl
functions decrement the
.Va v_holdcnt
of the vnode.
If the holdcount is less than or equal to zero prior to calling
.Fn vdrop
or
.Fn vdropl ,
the system will panic.
If the vnode is no longer referenced, it will be freed.
.Pp
.Fn vhold
and
.Fn vdrop
lock the vnode interlock while
.Fn vholdl
and
.Fn vdropl
expect the interlock to already be held.
.Sh SEE ALSO
.Xr vnode 9
.Sh AUTHORS
This manual page was written by
.An Chad David Aq Mt davidc@acns.ab.ca .
